1. Field of the Invention
The present invention relates to a damper lever for a grand piano which is used as a component for a damper assembly in a grand piano.
2. Description of the Related Art
A damper assembly in a grand piano is provided for releasing and clamping a string in association with operations on a keyboard and so on to allow sound to generate and prevent sound from generating. In this event, when a key on a keyboard is depressed, the damper lever of the damper assembly is directly driven by the key to rotate, causing a damper head coupled to the damper lever to rise so that the damper head is moved away from the string, thereby releasing the string before a hamper strikes the string to permit the string to vibrate, thus allowing sound to generate. On the other hand, after the depressed key is released, the damper lever rotates in the reverse direction by its own weight to cause the damper head to fall so that the damper head comes in contact with the string to hold the string from the above, thus stopping the sound from generating.
Referring now to FIG. 1, a damper lever 21 for a conventional grand piano is composed of a lever body 22 and a plurality of (for example, three) lead pieces 23 embedded in the lever body 22. The lever body is made of a solid wood such as maple, magnolia, or the like, and is made in a rectangular rod shape of a predetermined shape and dimension by cutting such wood. The lever body 22 is formed with a plurality of holes 24 for embedding lead pieces 23, a wire flange mounting recess 25 for mounting a wire flange (not shown), and so on by numerical control (NC) machining or the like. Each lead embedding hole 24, which has a dimension to exactly fit the lead piece 23 therein, is formed through the lever body 21 from one to the other surfaces. The lever body 22 is also provided with a pilot screw 26 with a tapping screw 26a attached to the bottom surface thereof for controlling the height of the damper lever 21 in order to appropriately adjusting the timing of stopping sound.
The lead pieces 23 are provided for increasing the self weight of the damper lever 21 to ensure that the damper lever stops sound after a key is released. Thus, each lead piece has a predetermined weight in accordance with an associated sound range and is formed in a cylindrical shape. The lead piece 23 is fixed in the lever body 22 by caulking. More specifically, as illustrated in FIG. 2A, the lever body 22 is placed on a base 27 with its side surfaces facing the upward and downward directions, and a lead piece 23 is inserted into the lead embedding hole 24. Subsequently, the tip of a tool 28 is placed on the exposed side surface of the lead piece 23, and the head of the tool 28 is struck with a hammer (not shown) to deform the lead piece 23 in the radial direction as illustrated in FIG. 2B. Thus, with a pressure produced by the striking, the entire outer peripheral surface of the lead piece 23 is brought into contact with the wall of the lead embedding hole 24 to fix the lead piece 23 in the lever body 22.
However, since the conventional damper lever 21 as mentioned above employs a rather expensive solid wood as the material for the lever body 22, it suffers from a high material cost. In addition, the machining required to form the lever body 22 with the lead embedding holes 24 and so on causes a higher machining cost. Further, since the lever body 22 is fabricated by cutting wood, an available accuracy in dimension is limited. To compensate for the low machining accuracy, it is necessary to finely control the height of the damper lever 21 with the pilot screw 26, thus requiring time and labor for the fine adjustment. Furthermore, since the lever body 22 is made of wood, its weathering resistance and strength are limited. For example, the influence of humidity and aging may cause deformation such as bowing and dimensional change in the lever body 22. In addition, during the control of the height of the damper lever 21 with the pilot screw 26, the thread formed in the bottom of the lever body 22 may be broken due to a clamping torque of the tapping screw 26 too large for the thread to withstand.
To solve the inconveniences as mentioned above, it may be envisioned that the wood be replaced with, for example, a relatively hard plastic material. However, since the plastic material generally has a toughness lower than wood, other inconveniences may be caused by the replacement of the material for the lever body 22. For example, an impact load applied to the lever body 22 when a lead piece 23 is caulked may cause a fracture in a caulked portion of the lever body 22, a deformation of the lever body as a whole, and so on.